.TH DUMP 1M 
.SH NAME
dump \- incremental file system dump
.SH SYNOPSIS
.B dump
[ key [ argument ... ] filesystem ]
.SH DESCRIPTION
.I Dump
copies to magnetic tape all files
changed after a certain date
in the
.I filesystem.
The
.I key
specifies the date and other options about the dump.
.I Key
consists of characters from
the set
.B 0123456789fusd.
.TP 5
.B  f
Place the dump on the next 
.I argument 
file
instead of the tape.
.TP 5
.B  u
If the dump completes successfully,
write the date of the beginning of the dump on
file `/etc/ddate'.
This file records a separate date for
each filesystem and each dump level.
.TP 5
.B  0\-9
This number is the `dump level'.
All files modified since the last date stored
in the file `/etc/ddate' for
the same filesystem at lesser levels
will be dumped.
If no date is determined by the level,
the beginning of time is assumed;
thus the option
.B 0
causes the entire filesystem to be dumped.
.TP 5
.B  s
The size of the dump tape is specified in feet.
The number of feet is taken from the next
.I argument.
When the specified size is reached,
the dump will wait for reels to be changed.
The default size is 2300 feet.
.TP 5
.B d
The density of the tape, expressed in BPI,
is taken from the next
.I argument.
This is used in calculating the amount of tape
used per write. The default is 1600.
.PP
.DT
If no arguments are given,
the
.I key
is assumed to be
.B 9u
and a default file system is dumped
to the default tape.
.PP
Now a short suggestion on how
perform dumps.
Start with a full level 0 dump
.PP
	dump 0u
.PP
Next,
periodic level 9 dumps should be made on an
exponential progression of tapes.
(Sometimes called Tower of Hanoi \- 1 2 1 3 1 2 1 4 ...
tape 1 used every other time,
tape 2 used every fourth,
tape 3 used every eighth, etc.)
.PP
	dump 9u
.PP
When the level 9 incremental approaches a full
tape (about 78000 blocks at 1600 BPI blocked 20),
a level 1 dump should be made.
.PP
	dump 1u
.PP
After this,
the exponential series should progress as uninterrupted.
These level 9 dumps are based on the level 1 dump which
is based on the level 0 full dump.
This progression of levels of dump can be carried
as far as desired.
.SH FILES
default filesystem and tape vary with installation.
.br
/etc/ddate: record dump dates of filesystem/level.
.SH "SEE ALSO"
restor(1), dump(5), dumpdir(1)
.SH DIAGNOSTICS
If the dump requires more than one tape,
it will ask you to change tapes.
Reply with a new-line when this has been done.
.SH BUGS
Sizes are based on 1600 BPI blocked tape.
The raw magtape device has to be used to
approach these densities.
Read errors on the filesystem are ignored.
Write errors on the magtape are usually fatal.
